University of Florida law professor Mark Fenster discusses the conspiracy theories surrounding the attacks of September 11, 2001, and the role such theories play in American society. Fenster is the author of Conspiracy Theories: Secrecy and Power in American Culture. In the wake of the attacks conspiracy theories abounded, including that the administration of former US president George W. Bush either had a hand in, or advance knowledge of, the attacks. Among other things, the conspiracy theorists – or 9/11 “truthers” – argued that the vertical collapse of the Twin Towers appeared to resemble a controlled demolition. US President Donald Trump remembered those aboard a fourth flight that crashed in a Pennsylvania field before it hit its target, praising passengers and crew who resisted the hijackers. "This field is now a monument to American defiance," Trump said. "This memorial is now a message to the world: America will never, ever submit to tyranny."